Add the turmeric, garam masala, and 2 teaspoons of the ground chile powder to the skillet. Reserve the remaining chile powder for another use. Saute the mixture for 30 seconds, then add the crushed tomatoes and 1/4 cup of the reserved tomato juice. Cook the mixture, stirring, until thickened and most of liquid is cooked out. Cook's Note: This sweetens the tomatoes and helps bring all the flavors together.

Strain the prawn shells from the water and discard the shells. The water is now a prawn stock. Add 2 cups of the prawn stock to the tomato mixture and bring the mixture to a simmer. The remaining prawn stock can be cooled and frozen for future use. Simmer the tomato mixture, uncovered, for 10 minutes.

Add the prawns to the skillet and cook, stirring gently, until just cooked through, about 4 minutes. Reduce the heat to low, then add the heavy cream and fresh dill. Let the mixture simmer, for 2 minutes more, stirring gently. Season with salt, and pepper, to taste. Serve the masala with warm naan.